Stator blade mounting structure for turbomachines

ABSTRACT

The internal surface of the casing of a turbomachine is formed with an internal circular rib machined with a circular bore terminating at an inwardly extending radial flange. The root portions of a circular series of stator blades are assembled in a blade mounting ring. The blades are restrained against axial and radial movement in the ring. The mounting ring, with the blades preassembled therein, is positioned in the casing bore and is fixed therein as by an annular member which is bolted to the casing in clamping engagement with the roots of the blades and serving to clamp the assembly in the casing.

United States Patent Huesgen et al.

[ June 18, 1974 STATOR BLADE MOUNTING STRUCTURE FOR TURBOMACHINES Carrier Corporation, Syracuse, NY.

Nov. 22, 1972 US. Cl. 415/217, 415/219 R Int. Cl. Fold l/02 [56] References Cited UNITED STATES PATENTS 2,935,296 5/1960 Hockert et al 416/220 FOREIGN PATENTS OR APPLICATIONS 776,988 6/1957 Great Britain 415/217 Field of Search 415/199 R,2l6,217,2l8,

1,010,300 11/1965 GreatBritain 415/218 Primary Examinerl-lenry F. Raduazo Attorney, Agent, or Firm.l. Raymond Curtin [57] ABSTRACT The internal surface of the casing of a turbomachine is formed with an internal circular rib machined with a circular bore terminating at an inwardly extending radial flange. The root portions of a circular series of stator blades are assembled in a blade mounting ring. The blades are restrained against axial and radial movement in the ring. The mounting ring, with the blades preassembled therein, is positioned in the casing bore and is fixed therein as by an annular member which is bolted to the casing in clamping engagement with the roots of the blades and serving to clamp the assembly in the casing.

4 Clains, 2 Drawing Figures I r tutti .LL '7 33 37 j a 22 40 I4 I I3 K all/ qlIll/l/l/(Z/ a STATOR BLADE MOUNTING STRUCTURE FOR TURBOMACHINES BACKGROUND OF THE INVENTION The conventional method of fixedly mounting stator blades in a turbine casing consists of machining a circumferentially extending slot in the inner surface of the casing. The slot is of T formation, or the like, and the roots of the stator blades are machined with a mating configuration so that the blades are interlocked with the casing. The blades are inserted individually in the T slot. With that method, it is difficult to machine the T slots in large casings and hold the machined surfaces true. Such machining and assembly is time consuming and expensive. Also, an extensive amount of time is consumed in removing the blades for replacement.

This invention has'as an object a stator blade mounting structure which results in a very substantial reduction in machining and assembly time andwhich provides for the ready and convenient removal and replacement of the stator blades.

SUMMARY OF THE INVENTION The turbine casing is formed with an internal circular rib. The rib is formed with a radially disposed end surface and with a cylindrical bore terminating man inwardly extending flange. A circular series of stator blades are assembled in a blade mounting ring. Means is provided for limiting movement of the assembled blades in axial and radial directions relative to the mounting ring. The mounting ring is positioned in the circular casing bore and retained therein by means including bolts threaded into the radial end surface of the casing rib.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partial sectional view of a turbine embodying our invention; and

FIG. 2 is a view taken on line 22, FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT In the turbine structure shown in FIG. 1, the casing of the turbine is indicated at and is formed with an inlet passage 11 and an exhaust passage 12. The casing is formed with an inwardly extending curved wall 13 defining in part the inlet 11. A diffuser section 1 4 is attached to the casing 10 as by screws, one of which is shown at 15, and forms in part the exhaust passage 12.

The casing 10 is formed intermediate the inlet and outlet passages 11 and 12 with an internal circular rib 17. The rib 17 is formed with a radially disposed end surface 18 and with a cylindrical bore 20 extending from the end surface 18 and terminating at an inwardly extending radial flange 21. A stator blade mounting ring 22 is positioned in the bore 20and a circularseries of stator blades is mounted in the ring 22,, see FIG. 2.

In practice, the stator blades 25 are preassembled in the ring 22. In the structure shown, the ring 22 is formed with a radial flange 23. The flange 23 of ring 22 is formed, on the surface confronting the stator blades 25, with a circular rib 30. The confronting surfaces of the blades 25 are formed with complemental notches whereby the blades 25' are restrained against radial movement relative to the ring 22.

Means is also provided to limit axial displacement of the preassembled blades 25 relative to the ring 22. The ring 22 is formed with a series of threaded apertures in which screws 33 are threaded. The inner ends of the screws 33 extend into apertures formed in the roots of the blades 25. These apertures are enlarged relative to the diameter of the screws 33 to permit limited movement of the blades axially in the ring 22, but the arrangement is effective to prevent detachment of the preassembled blades from the mounting ring 22.

The mounting ring 22 with the stator blades 25 preassembled therein is mounted in the bore 20 of the casing rib 17. Means is provided for fixedly securing the blades 25 in the mounting ring and the ring in the rib 17. Referring to FIG. 1 of the drawings, the securing means is in the form of an annular member 35 detachably secured to rib 17 of the casing by a series of screws 37 extending through the ring 35 and threaded into the rib 17. The axial dimension of the ring 22 is less than the axial length of the bore 20. The mounting ring 35 is formed with cylindrical portion 40 dimensioned for a close fit in the portion of the bore 20 outwardly of the ring 22 as shown in FIG. 1. The ring 35 is formed with an annular surface abutting against the stator blades 25. Accordingly, when the bolts 37 are tightened, the blades 25 are clamped against the flange 23 of ring 22 and the ring 22 clamped against the flange 21 of the rib 17.

The turbine blade carrying disc 43 is fixedly mounted on the shaft 45. The inner portions of the wall sections 13, 14 are formed with cylindrical bores to receive labyrinth sealing ring structures 50 engaging the shaft 45.

The rotor disc 43 carries a circular series of turbine blades 51 which are positioned on the downstream side of the stator blades 25 in adjacency thereto.

The securing ring 35 is formed with a shroud portion 57 encircling the tips of the turbine blades 51.

While we have described a preferred embodiment of our invention, it should be understood that the invention is not limited thereto, but may be otherwise embodied within the scope of the following claims.

We claim:

1. A stator blade mounting structure for turbomachines comprising a machine casing formed with a circular bore, a stator blade mounting ring positioned in said bore, a circular series of stator blades having root portions mounted in said mounting ring, said blades extending radially inwardly from said ring, securing means carried by said casing and engaging said blades for fixedly securing said blades in said mounting ring and fixedly clamping said mounting ring in said casing bore.

2. A stator blade mounting structure as defined in claim 1 and including means carried by said mounting ring and cooperable with the root portion of each of said blades initially assembled in said mounting ring to permit limited movement of the blades in a direction axially of said ring.

3. A stator blade mounting structure for turbomachines comprising a machine casing formed with an internal circular rib having a radial end surface, said rib being formed with a cylindrical bore extending from said end surface and terminating at an inwardly extending radial flange, a stator blade mounting ring positioned in said rib bore and having an inwardly extending radial flange abutting against said radial flange of said bore, a circular series of stator blades having root portions mounted in said mounting ring and extending radially inwardly therefrom, securing means detachably secured to said casing and engaging the root portions of said blades and operable to fixedly secure said 

1. A stator blade mounting structure for turbomachines comprising a machine casing formed with a circular bore, a stator blade mounting ring positioned in said bore, a circular series of stator blades having root portions mounted in said mounting ring, said blades extending radially inwardly from said ring, securing means carried by said casing and engaging said blades for fixedly securing said blades in said mounting ring and fixedly clamping said mounting ring in said casing bore.
 2. A stator blade mounting structure as defined in claim 1 and including means carried by said mounting ring and cooperable with the root portion of each of said blades initially assembled in said mounting ring to permit limited movement of the blades in a direction axially of said ring.
 3. A stator blade mounting structure for turbomachines comprising a machine casing formed with an internal circular rib having a radial end surface, said rib being formed with a cylindrical bore extending from said end surface and terminating at an inwardly extending radial flange, a stator blade mounting ring positioned in said rib bore and having an inwardly extending radial flange abutting against said radial flange of said bore, a circular series of stator blades having root portions mounted in said mounting ring and extending radially inwardly therefrom, securing means detachably secured to said casing and engaging the root portions of said blades and operable to fixedly secure said blades in said mounting ring and said mounting ring in said casing bore.
 4. A stator blade mounting structure as defined in claim 3 wherein said securing means includes an annular member secured to said end surface of said casing rib. 